Researchers said heightened race consciousness could in part explain the disproportionately high rate of hypertension among black Americans, whose blood pressure is among the highest in the world.

"A preoccupation with race among blacks leads to hyper-vigilance, a heightened awareness of their stigmatized status in society and a feeling that they need to watch their backs constantly," said Dr. Lisa Cooper, a professor in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine. She's also the senior author of the study described online in the American Journal of Hypertension.

Researchers surveyed 266 patients, 62 percent of whom were black, in urban health clinics in Baltimore between September 2003 and August 2005.

Patients were asked how often they thought about their race. Researchers said about half of the black patients responded that they think about it, while 1 in 5 white patients said they did.

Those black patients who said they were more race-conscious measured in with higher blood pressure rates than the black patients who said they weren't preoccupied with race. There was no effect on blood pressure in race-conscious white patients.

Researchers went on to say the problem doesn't seem to be genetic.

"While things like diet, exercise and reduced access to health care may contribute, we think that a tense social environment -- the sense of being treated differently because of your race -- could also possibly explain some of what’s behind the higher rates," Cooper said.

Cooper, who is black, said her son is very aware of his surroundings, especially in the wake of the killing of Florida teenager Trayvon Martin.

"It’s stressful for him to walk around thinking at any time someone might think he’s doing something wrong just because of his race," she said. "That’s just something he lives with. If you don’t live with it, maybe it’s hard to understand it. It’s something people often don’t want to talk about."

Cooper said it is well known that chronic stress can increase blood pressure.

More research is needed to understand the biological consequences of race consciousness, including those related to stress, with a goal of developing interventions to help people effectively cope with environmental stressors, Cooper said.

"We need to help people of all races cope with race-related stress in a healthier way," she said.

The study was supported by grants from the National Institutes of Health’s National Heart, Lung and Blood Institute.